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Advance Software Engineering (SEII). Lecture-1: Introduction. Objective.
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Advance Software Engineering(SEII) Lecture-1: Introduction
Objective The objective of this course is to learn techniques to manage the development of software projects. The success of a software project depends to a large extent on the project management principles and practices used in a software project. This course will provide the knowledge and skills to Software Development Process Models, Project Management Concepts, Project Metrics, Software Project Planning, Risk Analysis and Management, Project Schedules and Tracking, Software Quality Assurance, Requirement Engineering Processes and Software Re-engineering.
Recommended Books Pressman, R.S (2012) Software Engineering, A Practitioner’s Approach, 7th Edition, McGraw-Hill Software Engineering, 9th Edition, Addison-Wesley Reference Book Software Engineering by Sommerville Beatty, J and Wiegers, K. (2013) Software requirements, 3rd Edition, Microsoft Press, Sommerville, I. (2011)
Today We will cover • Introduction to Software Engineering • Software Production • Scope and Need of Software Engineering • Abstraction and Decomposition • Software Development Life Cycle • Waterfall Model • Spiral Model • Prototype Model • Introduction to Advance Software Engineering
Software Engineering Recall your previous knowledge of software engineering • Software engineering is an engineering approach that is concerned with all aspects of software production from the early stages of system specification through to maintaining the system after it has gone into use. • Software Engineering is the set of processes and tools to develop software. Software Engineering is the combination of all the tools, techniques, and processes that used in software production.
Software Engineering Software Engineering encompasses all those things that are used in software production like: • Programming Language • Programming Language Design • Software Design Techniques • Tools • Testing • Maintenance • Development etc.
Software Production Main activities in software production are given below: • Construction • Management
Construction The construction activities are those that directly related to the development of software, e.g. gathering the requirements of the software, develop design, implement and test the software etc. Some of the major construction activities are listed below. • Requirement Gathering • Design Development • Coding • Testing
Management Management activities are kind of umbrella activities that are used to smoothly and successfully perform the construction activities e.g. project planning, software quality assurance etc. Some of the major management activities are listed below. • Project Planning and Management • Configuration Management • Software Quality Assurance • Installation and Training
Scope and Need of Software Engineering • Software engineering is a systematic collection of past experience. The experience is arranged in the form of methodologies and guidelines. • A small program can be written without using software engineering principles. But if one wants to develop a large software product, then software engineering principles are MUST to achieve a good quality software cost effectively.
Scope and Need of Software Engineering • Without using software engineering principles it would be difficult to develop large programs. • A program of size 1,000 lines of code has some complexity. But a program with 10,000 LOC is not just 10 times more difficult to develop, but may as well turn out to be 100 times more difficult unless software engineering principles are used. • In such situations software engineering techniques come to rescue. • Software engineering helps to reduce the programming complexity. • Software engineering principles use two important techniques to reduce problem complexity.
Basic Concepts of SE Abstraction • The principle of abstraction implies that a problem can be simplified by omitting irrelevant details. • In other words, the main purpose of abstraction is to consider only those aspects of the problem that are relevant for certain purpose and suppress other aspects that are not relevant for the given purpose. • Once the simpler problem is solved, then the omitted details can be taken into consideration to solve the next lower level abstraction, and so on. • Abstraction is a powerful way of reducing the complexity of the problem.
Basic Concepts of SE Decomposition • In this technique, a complex problem is divided into several smaller problems and then the smaller problems are solved one by one.
Decomposition • However, in this technique any random decomposition of a problem into smaller parts will not help. • The problem has to be decomposed such that each component of the decomposed problem can be solved independently and then the solution of the different components can be combined to get the full solution. • A good decomposition of a problem should minimize interactions among various components. • If the different subcomponents are interrelated, then the different components cannot be solved separately and the desired reduction in complexity will not be realized.
Software Development Life Cycle Model • A software life cycle model (also called process model) is a descriptive and diagrammatic representation of the software life cycle. • A life cycle model represents all the activities required to make a software product. • It also captures the order in which these activities are to be undertaken. • In other words, a life cycle model maps the different activities performed on a software product from its start to retirement.
Need of Software Life Cycle Model • Without using of a particular life cycle model the development of a software product would not be in a systematic and disciplined manner. • When a software product is being developed by a team there must be a clear understanding among team members about when and what to do. Otherwise it would lead to chaos and project failure.
Different Software Life Cycle Model • Many life cycle models have been proposed so far. Each of them has some advantages as well as some disadvantages. A few important and commonly used life cycle models are as follows: • Classical Waterfall Model • Prototyping Model or Evolutionary Model • Spiral Model
Classical Waterfall Model • The classical waterfall model is intuitively the most obvious way to develop software. • Thus, this model can be considered to be a theoretical way of developing software. • But all other life cycle models are essentially derived from the classical waterfall model. So, in order to be able to appreciate other life cycle models it is necessary to learn the classical waterfall model.
Prototype Model • A prototype is a toy implementation of the system. • A prototype usually exhibits limited functional capabilities, low reliability, and inefficient performance compared to the actual software. • A prototype is usually built using several shortcuts. The shortcuts might involve using inefficient, inaccurate, or dummy functions. • A prototype usually turns out to be a very crude version of the actual system.
When to use Prototype Model • A prototype of the actual product is preferred in situations such as: • user requirements are not complete • technical issues are not clear • Example 1: User requirements are not complete : In any application software like billing in a retail shop, accounting in a firm, etc the users of the software are not clear about the different functionalities required. Once they are provided with the prototype implementation, they can try to use it and find out the missing functionalities. • Example 2: Technical issues are not clear Suppose a project involves writing a compiler and the development team has never written a compiler. In such a case, the team can consider a simple language, try to build a compiler in order to check the issues that arise in the process and resolve them. After successfully building a small compiler (prototype), they would extend it to one that supports a complete language.
Spiral Model • The spiral model is called a meta model since it encompasses all other life cycle models. • Risk handling is inherently built into this model. The spiral model is suitable for development of technically challenging software products that are prone to several kinds of risks. • However, this model is much more complex than the other models – this is probably a factor deterring its use in ordinary projects.
Summary • What is Software Engineering • Software Production • Scope and Need of Software Engineering • Abstraction and Decomposition • Software Life Cycle Model • Waterfall • Prototype • Spiral